These corrective actions range from more effective management of ventilation in buildings in the least serious cases right through to directly extracting the gas from the subsoil (before it manages to seep inside the premises) in cases where levels are higher. Radon filters in from the ground through cracks in the foundations, walls and the plumbing in bathrooms. Including architectural barriers that are impermeable to the gas are recommended in newly constructed buildings.
Llerena explains the process: "The first thing is to identify whether there is a problem. After this, detailed measurements will be taken to find out the entry points for the gas. On the basis of these data, suggestions will be made about whether simply to improve ventilation or to carry out more in-depth work, for example making the building gas-impermeable or draining radon from the subsoil before it can get into the building. Each building is a world unto itself".
The soils in Galicia have high potential for radon emission, since they overlie an area of fractured granite. Exposure to this natural radioactive element occurs, above all, as a result of inhaling it in poorly-ventilated premises, although it can also be ingested if it is present dissolved in water.
FECYT - Spanish Foundation for Science and Technology